Underwater breathing apparatus



Aug. 1959 DE Loss L. MARSH 2,900,977

UNDERWATER BREATHING APPARATUS Filed May 31, 1955 l FIG -4 INVENTOR. a flelaii L/Vdr-Jfi United States Patent 2,900,977 UNDERWATER BREATHING APPARATUS De Loss L. Marsh, Hayward, Calif. Application May 31, 1955, Serial No. 512,223 1 Claim. (Cl. 128-142) This application relates to a breathing apparatus. More particularly, the application is directed to a breath ing apparatus of the semiclosed circuit type designed for use in skin diving.

The closed circuit type of breathing apparatus is that type wherein all of the air exhaled by the wearer on each breath is purified, collected in a breathing bag, and re-inhaled by the wearer at the next succeeding inhalation. In the open circuit type of breathing apparatus, a pressurized reservoir of air, or oxygen mixed with an inert gas, is provided. Air is drawn from the reservoir on each inhalation through suitable pressure-reducing and demand valves and is exhausted into the ambient medium on exhalation.

The open circuit type of breathing apparatus automatically compensates for difi'erences in pressure as the diver moves downwardly and upwardly. With the use of this type of circuit, the diver may descend to depths of up to 300 feet without worrying about any toxic eifect which can be caused by excessive amounts of oxygen under pressures above two atmospheres. However, the open type circuit is very inefficient since all of the air breathed is discarded at every exhalation. This type of system requires large capacity high-pressure storage tanks for deep or sustained diving.

The closed circuit type of breathing apparatus is very eificient, since the same air is purified by having the carbon dioxide removed therefrom and oxygen added thereto from relatively small high-pressure cylinders of pure oxygen. However, the closed circuit type of apparatus does not automatically adjust to difierent pressures, and the wearer must constantly be changing the bag volume to maintain proper buoyancy and readjusting the oxygen inlet valve to guard against oxygen poisoning.

The semiclosed circuit disclosed herein is a combination of the two circuits described above and incorporates the automatic depth adjusting feature of the open circuit type while increasing the eificiency thereof by rebreathing a substantial portion of the air exhaled, and admitting only enough air from the high-pressure air reservoir to make up the oxygen consumed by the body.

It is well known, that the body uses only about onefifth of the oxygen taken into the lungs on any one inhalation. Therefore it is possible to rebreathe substantially four-fifths of the air exhaled, and only approximately one-fifth the total volume of an inhalation need be new air admitted to the system; provided, of course, that the carbon dioxide is removed from the rebreathed air. Since this type of circuit uses high-pressure air as does the open circuit type, the danger of oxygen poisoning is absent. The time limit for the use of this semiclosed circuit for a given capacity air cylinder is approximately five times that of the open circuit.

It is the principal object of this invention to provide a breathing apparatus of the semiclosed circuit type,

.wherein the amount of new air admitted to the system Fig. 3.

Referring now to the drawings wherein similar reflCc at each inhalation is controlled by the volume of the breathingbag.

Another object of the invention is to provide a breathing apparatus such as set forth above, whereina mechanical inlet valve controls the admission of new air to the system, and wherein said mechanical valve is actuated by the collapse of the breathing bag.

A further object of the invention is to provide a breathing apparatus such as set forth in the first object described above, wherein the admission of new air to the system is controlled by a differential pressure-actuated demand valve located at a point higher on the apparatus than the breathing bag, whereby the hydrostatic pressure on the valve will be less than that on the bag, so that the valve will not open until the bag has been completely collapsed.

The preferred embodiments of the invention are described in the following detailed specification, and illustrated by way of example in the accompanying drawings, wherein:

Fig. 1 is a rear view of one form of breathing apparatus embodying the principles of the invention.

Fig. 2 is a side view of the embodiment shown in Fig. 1, with certain parts being shown in section, taken generally in the line 22 of Fig. 1..

apparatus as shown in Fig. 1.

Fig. 4 is a side view of the modification shown in erence numerals are used to denote the same elements throughout the various views shown, and referring more particularly to Figs. 1 and 2 thereof, the breathing apparatus 10 generally comprises a mouthpiece 11, a carbon dioxide absorbing canister 12, a breathing bag 13, and a high-pressure air cylinder 14.

The mouthpiece 11 is connected to the breathing bag 13 by a flexible tube 15 and to one side of the canister 12 by a flexible tube 16. The other side of the canister 12 is connected to the breathing bag 13 by a tube 17. In order to maintain the correct direction of air flow the tube 15 is provided with a check valve 18 to permit air to pass from the tube 15 to the mouthpiece 11 but not in the opposite direction. Similarly, the tube 16 is provided with a check valve 19 which permits air to pass from the mouthpiece 11 into the tube 16 but not in the correct size of the breathing bag may be obtained by se-- lecting one of a proper size from a supply of different size breathing bags of the type illustrated at 13 in Figs. 1 and 2, or the bag may be of the adjustable volume type such as shown at 13' in Figs. 3 and 4 hereinafter described. In any case, it is essential that the bag be somewhat smaller in volume than the normal volume of one breath of the user.

Referring again now to Fig. 2, the breathing bag 13 is of the accordion bellows type, and is provided with a metal striker plate 20 centrally located on the inner surface of the movable wall of the bag. The bag is enclosed in a metal protective housing 21, provided with a plurality of breathing ports 22a to permit the ambient fluids to pass freely in and out of said housing. An exhaust valve 29 is provided on the breathing bag adjacent the lowermost portion thereof to permit the excess air expelled from the lungs to exhaust after the bag 13 is fully expanded.

In order to supply make-up fresh air from the cylinder 14, a port 22 connects the breathing bag 13 to the cylinder 14 through a suitable check valve 23 and pressure-reducing valve 24. The pressure-reducing valve 24 is set to Patented Aug. 25, 1959 maintain a *pres'sufe in' 'the-valve chamber 25 slightly gether the lowermost port'on to decrease the effective greater-than that within the breathing -bag- 13, -and-the- I check valve 23 is normally held in its closed position.

In the use of the device, as'disclosed in Figs, 1 and 2,

the apparatu's' is arranged am the back ofthe wearerwith the breathing bag at the same level and as nearlas possibl'etdihe lungs.'-. Airisexpelled from tlreidngs thiou h th mouthpiece'11f the' check valve '19,the tube/' 1 6; the caniste'r '12, and thetube 17 into the-breathing bag 13 and-' expands th'e' bag When the bag- 'is fully exp'anded, theexcess air is expelldintothe ambient fluid through the ex haust valve 297 Upon inhalation; air is= drawn into the lungs from rhe bag=13 through the tube= 15y the check valve 18,"' and'=the mouthpiece-11. When the-bag- *13 1s al mo'st completel-y collapsed, 'the striker plate 20 strike's*the end ofi 'the ste'm fid and opens the valve23' to permit air froni th cylinder'fl to flow into thebag andmepl'aee the air expelle'd therefrom duringthe exhalation."

Tui ni'rig now to the"modification showninFigs. 3 and 4, the breathing apparatus 10' is generally the same asthatshown in Figs. 1 and 2 with the=exceptions that a different type ofcanister 12' 'andbreathing 'bag -13- 1 are shown; and a differential pressure actuated demand valve 26 is substituted for the mechanically operated-valve 23 ofFigskl and 2. In-this-system;=-the' reducing valve24 is set-to ma intain a pr eSsure'sIi-ghtly less-than'-that in the 1 citculating -system so -that the demand" valve 26 is normal- IWcIO'sed a'ndopensonly when thebag13- l is completely empty and further inhalation decreases the pressure "in-the" system below the setting -ofi the pressure '-reducing=- valve 24. Diflferential pressure valves capable of functioning in the manner described above are commercially available and further description thereof is not deemed necessary herein:f The demancl'valve ZG- islocated so that in the normaliswimming or upright position the' demand valve will-lbe higher than the breathingbag and therefo're'iat a lowerrhydrostatic pressure than the-breathingbag 13'1" Inith'e operation 'of= the systerr'i shown in -Figs. 3 and 4, the :air: 1 exhaled passes through: the: mouthpiece 11, the valve 19, and the tube 16,-into the carbon dioxide absorbing-:section 27 bf-:the canister- 12; Afterpa's'sing through the t carbon dioxide 1 absorbingmaterial, the air passes througlr the' tube 17 into the-breathing bag 13" and the errcess is' expelled through the'exhaustvalve 29in the same manner-as described-above with respect 'to' Figs; 1 'and-2."

' Upon subsequent inhalation, 1 air passes from the bag l3' through the 'tube'17 into the'plenum'chamber 2813f" the" canister 12'Z Fromtheplenum"chamb'er28, the*air passes through the tubeand the check valve18 to the mouthpiece 11 When the bag 13"is-completely' collapsed, the pressure in the plenum chamber 28is decr'e'asedand the demand valve 26 opens to permit 'air from th 'cylinder 14 toenter the plenum chamber? The bag 13' may be'adjustedto conformto the various lung capacities of diflerent individuals by clamping" to- From the foregoing description, it may be seen that I have provided a'novel semiclosed circuit, self-contained breathing apparatus combining the advantages of automatic depth compensation and freedom from possible oxygen poisoning inherent in the open circuit type of apparatus, and the extended capacity of the closed circuit type of apparatus, while eliminating the dangerous or undesirable disadvantage's'ofeachr Even thoughtwo different types-of: canisters and two types of breathing'bags are shown in the two embodiments, itis to' be understood that either 'of the canisters shown, or either oflthe breathing bagsshown, may be employed in each of the two modifications. The essential difierence between the modifications is found in the use of either a mechanically actuated or a differential pressureoperated demand valve.

While l have shown and described=-thdprefehr'ed forms 7 of the inventiom it is obvious that various changesi may be'--made in its construction-' by those skilled 'inthe without departing from the spirit of the inventionashe fined in the appended 1 claims Having thus described my inventionywhat I claimand desire to secure by Letters Patent -is:=--

In a breathing apparatus; a circulating system comprise in-g amouthpiece" a carbon v dioxide absorbing canistenf a breathing-bag, :said breathing ba'g--being --smaller than the volume of air breathed during one-inhalation: f t 6 person using th'e device; a: flexible :tube connecting said mouthpiece to oneside-of said canister; means inchidiiigfi a flexible tube connecting the other side of said canisteifil to 'sa'id breathin'g bag, means including a flexi'ble tube conne'ctingsaid mouthpiece: to said breathing .bag, a checks valve in ieach of said :br'e'a'thingiflexible tubes, anexhausts check valv'e =inisaid breathingibag' adjacent the lowermostportion there'cfli an air storage cyli'nde'r; a :cond'uit' meeting said cylinder with said system, a normally iclosed' l demand valve in said 'conduimsaid demand yalyehaving a' stem protruding into said breathirig bag, and a-st'riker pl'ate' fixed to the inner: surface ofsaidbagaoppositesaid stem-,2 whereby when 1 said bagis collapsed 7 said striker plate will strike said stem to open'sa'id valyeto permit r froirr 'said 'g'cylinderto' enter said circulating system;

Reference'sCited-inthe file of this patent UNITED; STATES "PA'I-ENTS 2,300,273" connell Oct."27', "1922" 2,269,5001 Wildhack" Jan. 13,1942

2,732,840. De Sanctis i Jan. 31, 1956'- FOREIGN: PATENTS 893,295 Germany Oct. 15, I953 894;81-2 Gennany n-naau- OCiEr29, 1953 9013627 Germany Jan.'-14, 1954* 

